Describing the oil giant’s role in the disaster, a US judge in a civil case has ruled that BP was “grossly negligent and “reckless”.

The case follows an earlier criminal prosecution, which saw the company plead guilty to 14 criminal charges.

A rig explosion caused the biggest offshore spill in US history which lasted almost three months and affected several states’ coastlines.

US Attorney General Eric Holder said the prosecution would send a strong message to industrial giants: “This case, which was vigorously pursued by the United States’ stellar legal team, marks another significant step forward in the Justice Department’s continuing efforts to seek justice on behalf of the American people for this disaster, and we are confident that this will work as a strong deterrent to anyone who is tempted to sacrifice safety and the environment in the pursuit of profit.”

BP has already been fined about $42 billion in other legal cases and has vowed to appeal this ruling which puts most of the blame for the tragedy on the company.

Eleven workers were killed and millions of barrels of crude oil were released into the Gulf of Mexico.

BP’s shares slumped 5.9 percent in reaction on Thursday, but steadied on Friday.

Analysts said the sell off was overdone, as the level of fines may not be determined for years and BP will likely be able to pay them without any major asset sales, or a big cut to its dividend.